Aluminum Phthalocyanine Research Articles

Silica gel-immobilized aluminum phthalocyanine complex as a heterogeneous catalyst for the synthesis of α-amino phosphonates

Aluminum phthalocyanine complexes immobilized onto silica gel (CPG-550 is controlled pore glass, MCM-41 is mesoporous molecular sieves) exhibited high catalytic activity and stability in the Kabachnik—Fields reaction.

Low-bandgap small molecules for near-infrared photovoltaic applications

We investigate the effects of interfacial layers on the photovoltaic properties of bi- layer organic heterojunction photovoltaic devices. The devices were fabricated using aluminum phthalocyanine chloride (AlPcCl) as electron donor and fullerene (C60) as electron acceptor. Two types of interfacial layers inserted between the transparent indium-tin-oxide anode and the AlPcCl layer were investigated: PEDOT:PSS and MoO3. We find that these interfacial layers have a strong influence on the device open-circuit voltage (VOC). The effects of temperature and illumination intensity on VOC were explored. C 2011 Society of Photo-Optical Instrumentation

In vitro and in vivo targeted delivery of photosensitizers to the tumor cells for enhanced photodynamic effects

Efficacy of photodynamic therapy can be enhanced by improving uptake, localization, and sub-cellular localization of sensitizers at the sensitive targets. Uptake, localization, and photodynamic effects of hematoporphyrin derivative (HpD, Photosan-3; PS-3) and disulfonated aluminum phthalocyanine (AlPcS₂) were studied either encapsulated in liposomes or conjugated to a monoclonal antibody to carcinoembryonic antigen (anti-CEA) in a brain glioma cell line, BMG-1. Although the total uptake with encapsulated or conjugated sensitizers was less than the free sensitizers, photodynamic efficiency was higher due to the localization of the sensitizer at the sensitive targets. Biodistribution of intravenously administered technetium (⁹⁹m Tc)-labeled PS-3 analyzed by gamma camera imaging showed maximum accumulation in the liver followed by tumor. Tumor/muscle (T/N) ratio of free PS-3 was higher compared to encapsulated or conjugated PS-3 but the accumulation of PS-3 significantly reduced in brain and cutaneous tissue following modulated delivery. Pharmacokinetics suggested faster accumulation of encapsulated and conjugated PS-3 in the tumor. Localization of sensitizers at sensitive targets and reduced accumulation in normal tissues with liposome encapsulation and antibody conjugation suggest that these two delivery systems can potentially enhance the efficacy of photodynamic treatment.

Assessment of Leishmania major and Leishmania braziliensis promastigote viability after photodynamic treatment with aluminum phthalocyanine tetrasulfonate (AlPcS4)

Cutaneous leishmaniasis is an infectious disease caused by protozoans of the genus Leishmania, which is transmitted through the bite of hematophagous insects of the genus Lutzomyia. This study aimed at testing in vitro the phototoxic effect of aluminum phthalocyanine tetrasulfonate (AlPcS4) on the viability of Leishmania major and Leishmania braziliensis. Stationary phase promastigote forms were treated with AlPcS4 at 1.0 µM and 10.0 µM and incubated for one hour. Then 659 nm laser was applied at 5 and 10 J/cm². Parasite viability was determined by differential count using the trypan blue dye exclusion method and by monitoring growth curves for nine days. Trypan blue exclusion assay showed a significant reduction of viable parasites compared to controls, L. major seemed more sensitive to the toxic effects of AlPcS4 in the dark. The most effective photodynamic therapy (PDT) was obtained with AlPcS4 at 10.0 µM and 10 J/cm² whereas L. braziliensis showed the highest mortality rate after treatment.

New MEH-PPV Based Composite Materials for Rewritable Nonvolatile Polymer Memory Devices

ABSTRACTWe present the memory performance of devices with bistable electrical behavior based on MEH-PPV (Poly (1-methoxy-4-(2-ethylhexyloxy)-p-phenylenevinylene)) containing metal (Zn or Fe-Ni) particles. Another memory device based on aluminum phthalocyanine chloride (PcAlCl) added to the composite material reveals the photoinduced switching, in addition to the electrical one. Possible mechanisms for resistive switching are discussed.

Synthesis of magnetic, fluorescent and mesoporous core-shell-structured nanoparticles for imaging, targeting and photodynamic therapy

A synthetic method to prepare novel multifunctional core-shell-structured mesoporous silica nanoparticles for simultaneous magnetic resonance (MR) and fluorescence imaging, cell targeting and photosensitization treatment has been developed. Superparamagnetic magnetite nanoparticles and fluorescent dyes are co-encapsulated inside nonporous silica nanoparticles as the core to provide dual-imaging capabilities (MR and optical). The photosensitizer molecules, tetra-substituted carboxyl aluminum phthalocyanine (AlC4Pc), are covalently linked to the mesoporous silica shell and exhibit excellent photo-oxidation efficiency. The surface modification of the core-shell silica nanoparticles with folic acid enhances the delivery of photosensitizers to the targeting cancer cells that overexpress the folate receptor, and thereby decreases their toxicity to the surrounding normal tissues. These unique advantages make the prepared multifunctional core-shell silica nanoparticles promising for cancer diagnosis and therapy.

Plasmonic Gold Nanorods Can Carry Sulfonated Aluminum Phthalocyanine To Improve Photodynamic Detection and Therapy of Cancers

Hexadecyltrimethylammonium bromide-coated gold nanorods (AuNRs) with positive charges were effectively bound to negatively charged sulfonated aluminum phthalocyanine (AlPcS), a photosensitizer for photodynamic detection and therapy, due to the electrostatic force, with a loading content of 10(4) AlPcS molecules per rod. A 5-fold increase in the AlPcS fluorescence of the AlPcS-AuNRs complex was seen. The excitation fluorescence spectrum of the AlPcS-AuNRs with a typical 520 nm band fits well with the resonance band of AuNR surface plasmons, suggesting that such increased AlPcS fluorescence is produced from the strong surface plasmons of AuNRs. The intracellular distribution of AlPcS-AuNRs was studied in the QGY liver cancer cells by respectively imaging the AlPcS fluorescence and AuNRs reflectance with a confocal microscope. Furthermore, the AlPcS-AuNRs-loaded cells were photodynamically damaged after being exposed to red light in a light-dose-dependent manner. In contrast, no phototoxicity of the cells was seen after incubation with the same amount of free AlPcS, indicating that the AlPcS-AuNRs can enhance the AlPcS-mediated photodynamic effect. In addition, the loaded AlPcS can be photothermally released from AuNRs in the cells by the irradiation with an 800 nm femtosecond laser, demonstrating the potential for controlled drug release.

Theoretical investigation of nitric oxide interaction with aluminum phthalocyanine

Nitric oxide (NO) is an extremely toxic compound formed during combustion, predominantly at high temperatures, and it is among the most important atmospheric pollutants. However, this compound has interesting biological activities, since it can control important biological processes in living organisms. With the aim of developing new materials that can be used as selective chemical sensors or as biomedical NO delivery agents we carried out a quantum mechanical study of the interaction of NO with aluminum phthalocyanine (AlPc) at B3LYP/6-31G* level. The calculation results show clearly that the complexation of NO with AlPc depends on the latter's oxidation state. NO is more strongly bonded to AlPc in the reduced state (−33.77 kcal/mol) than in the oxidized state (−4.96 kcal/mol). By applying the Fukui function and analysis of the Frontier molecular orbital, it was possible to explain the situation within which nitric oxide interacts with AlPc.

Study on the photostability of water-soluble Zn(II) and Al(III) phthalocyanines in aqueous solution

The photodegradation of a series of water-soluble Zn(II) and Al(III) phthalocyanines has been studied in aerobic aqueous solutions. The photobleaching quantum yields of zinc phthalocyanine derivatives range from 2.2 × 10-4 for octacarboxy- to 1.5 × 10-5 for ZnPc , bearing 16 positively charged groups on periphery. Their aluminum counterparts are more photostable and photobleach with quantum yields in the narrow range (0.75 ÷ 2 × 10-6). The pH dependences of the photobleaching quantum yields for aluminum phthalocyanines show enhanced photodegradation for molecules with deprotonated axial H2O ligand. Some aspects of the mechanism of dyes photodegradation were studied and discussed. It was found that contribution to photooxidation of type II pathways depends upon a particular dye structure. Thus, no contribution of singlet oxygen to the photooxidation of cationic phthalocyanines has been found, even though singlet oxygen is involved in the photodegradation of negatively charged phthalocyanines.

Single-Molecule Fluorescence of a Phthalocyanine in PAMAM Dendrimers Reveals Intensity−Lifetime Fluctuations from Quenching Dynamics

We report on single-molecule fluorescence of an aluminum phthalocyanine dye associated with PAMAM dendrimers at a glass surface. The fluorescence decays of the phthalocyanine−dendrimer complex depo...

Theoretical investigation of the interaction of glycerol with aluminum and magnesium phthalocyanines

Glycerol is a byproduct produced in great quantity by biodiesel industries in transesterification reactions. Finding new applications for glycerol is a current concern of many research groups around the world. This work focuses on a theoretical investigation, at the B3LYP/6-31G* level of theory, into the possibility of using aluminum phthalocyanine (AlPc) and magnesium phthalocyanine (MgPc) in the modelling of catalysts to convert glycerol into alcohol, which has wider industrial applicability. According to our calculations there are strong interactions between the O-terminus of glycerol and the central metal atom of AlPc and MgPc. By applying the Fukui function, HSAB theory and analysis of the frontier molecular orbital, it was possible to explain the way in which glycerol interacts with AlPc and MgPc. As a result of these interactions, there is a considerable change in both electronic and geometric parameters of glycerol, which can be used in designing new strategies to convert glycerol into alcohol.

Comparative in vitro study on the characteristics of different photosensitizers employed in PDT

At present a wide range of photosensitizers are employed in photodynamic therapy (PDT) that have very different characteristics. Although, countless in vitro studies on the attributes of photosensitizers do exist, a direct comparison of these substances on one cell line are rare and may contribute to the choice of the optimal photoactive substance for a specific application. We therefore evaluated the properties of six widespread photosensitizers, namely Foscan®, Fospeg®, hypericin, aluminum (III) phthalocyanine tetrasulfonate chloride (AlPcS 4), 5-aminolevulinic acid (ALA), and Photofrin® in terms of: (i) cytotoxicity without illumination, (ii) phototoxicity, (iii) cellular uptake and release, and (iv) apoptosis induction in A431 human epidermoid carcinoma cells using comparable illumination regimens. We clearly show that meso-tetrahydroxyphenylchlorin (mTHPC, Foscan®) is a very effective photosensitizer inducing high phototoxicity at very low concentrations. Similar in vitro characteristics and phototoxicity were observed for Fospeg®, the water-soluble formulation of mTHPC. Hypericin, a photosensitizer extracted from plants of the Hypericum genus, is very effective in inducing apoptosis over a wide range of light fluences. AlPcS 4 absorbs light of 674 nm wavelength providing a higher penetration depth in tissue. Its hydrophilic character allows for application as aqueous solution. ALA can be administered at very high concentrations without producing cytotoxic effects in the dark. The intracellular concentration of protoporphyrin IX rapidly decreases after withdrawal of ALA, thus minimizing the period of light sensitivity post PDT. Among all photosensitizers Photofrin® has most clinical approvals and serves as standard.

Application of aluminum phthalocyanine nanoparticles for fluorescent diagnostics in dentistry and skin autotransplantology

This paper deals with the possibility of application of aluminum phthalocyanine (AlPc) nanoparticles in clinical practice. AlPc fluoresces in the molecular form but in the form of nanoparticles it does not. Separation of molecules from an AlPc nanoparticle and therefore the appearance of fluorescence occurs under the effect of a number of biochemo-physical factors. Owing to this feature the application of AlPc nanoparticles followed by the measurement of fluorescence spectra is proposed as a diagnostics method. It was shown that after AlPc nanoparticle application on a tooth surface the fluorescence intensity in the enamel microdamage area is 2-3 times higher than that in the normal enamel area. The appearance of fluorescence after application of AlPc nanoparticles on skin autografts testifies to the presence of inflammation.

Non-monotonic changes in clonogenic cell survival induced by disulphonated aluminum phthalocyanine photodynamic treatment in a human glioma cell line

BackgroundPhotodynamic therapy (PDT) involves excitation of sensitizer molecules by visible light in the presence of molecular oxygen, thereby generating reactive oxygen species (ROS) through electron/energy transfer processes. The ROS, thus produced can cause damage to both the structure and the function of the cellular constituents resulting in cell death. Our preliminary investigations of dose-response relationships in a human glioma cell line (BMG-1) showed that disulphonated aluminum phthalocyanine (AlPcS2) photodynamically induced loss of cell survival in a concentration dependent manner up to 1 μM, further increases in AlPcS2concentration (>1 μM) were, however, observed to decrease the photodynamic toxicity. Considering the fact that for most photosensitizers only monotonic dose-response (survival) relationships have been reported, this result was unexpected. The present studies were, therefore, undertaken to further investigate the concentration dependent photodynamic effects of AlPcS2.MethodsConcentration-dependent cellular uptake, sub-cellular localization, proliferation and photodynamic effects of AlPcS2 were investigated in BMG-1 cells by absorbance and fluorescence measurements, image analysis, cell counting and colony forming assays, flow cytometry and micronuclei formation respectively.ResultsThe cellular uptake as a function of extra-cellular AlPcS2 concentrations was observed to be biphasic. AlPcS2 was distributed throughout the cytoplasm with intense fluorescence in the perinuclear regions at a concentration of 1 μM, while a weak diffuse fluorescence was observed at higher concentrations. A concentration-dependent decrease in cell proliferation with accumulation of cells in G2+M phase was observed after PDT. The response of clonogenic survival after AlPcS2-PDT was non-monotonic with respect to AlPcS2 concentration.ConclusionsBased on the results we conclude that concentration-dependent changes in physico-chemical properties of sensitizer such as aggregation may influence intracellular transport and localization of photosensitizer. Consequent modifications in the photodynamic induction of lesions and their repair leading to different modes of cell death may contribute to the observed non-linear effects.

The synthesis and photophysical properties of novel cationic tetra pyridiloxy substituted aluminium, silicon and titanium phthalocyanines in water

This work reports on the synthesis, characterisation and photophysical properties of new unquaternized β-2,(3)-tetra-(2 pyridiloxy) aluminium(III) ( 3a), silicon(IV) ( 3b), titanium(IV) ( 3c) phthalocyanines and their water-soluble quaternized counterparts, 4a, 4b and 4c, respectively. The water-soluble silicon(IV) ( 4b) and titanium(IV) ( 4c) phthalocyanine derivatives were found to be aggregated in aqueous media but were partially or fully disaggregated in the presence of a surfactant Cremophor ® EL (CEL). The photophysical properties of aggregated complexes were investigated both in the presence of CEL and in pH 11 alone. Low triplet and fluorescence yield were obtained in pH 11 but an improvement was achieved upon addition of CEL for the aggregated complexes. The unquaternized silicon(IV) phthalocyanine complex ( 3b) gave the highest triplet quantum yield of 0.77 in DMF followed by its quaternized derivative ( 4b) with triplet yield of 0.73 in pH 11 plus CEL. The highest triplet lifetime of 220 μs was obtained for 4b in the presence of CEL. Higher fluorescence yields of 0.23 were obtained for quaternized water-soluble aluminium(III) phthalocyanine derivative ( 4a) in the presence of CEL.

Measurement of the distribution of aerosols among mouse lobes by fluorescent imaging

Lung samples were prepared to investigate the perturbing effects of light absorption for quantifying the fluorescence signal of aluminum phthalocyanine tetrasulfonic acid (AlPCS). Standard solutions of known concentration and depth were imaged with different exposure times and analyzed. The intensity was found to be a linear function of concentration, depth, exposure time, and area. Mice were exposed to an aerosol of AlPCS with a mass median aerodynamic diameter of 390nm and geometric standard deviation of 1.8. Images of intact lung lobes and lung homogenates were obtained and then analyzed to allow quantifying the concentration of AlPCS among the lung lobes and trachea. For the distribution of aerosols, the results indicate that the concentration was uniform among the different lobes. Combining the quantitative analysis of the concentration with image analysis of the area/thickness, the mass deposited in each lobe was readily determined. This approach provides a quantitative means to determine the selectivity of drug delivery to mouse lower respiratory tract.

Solid-state 27Al nuclear magnetic resonance investigation of three aluminum-centered dyes

We report the first solid-state 27Al NMR study of three aluminum phthalocyanine dyes: aluminum phthalocyanine chloride, AlPcCl (1); aluminum-1,8,15,22-tetrakis(phenylthio)-29H,31H-phthalocyanine chloride, AlPc(SPh)4Cl (2); and aluminum-2,3-naphthalocyanine chloride, AlNcCl (3). Each of these compounds contains Al3+ ions coordinating to four nitrogen atoms and a chlorine atom. Solid-state 27Al NMR spectra, including multiple-quantum magic-angle spinning (MQMAS) spectra and quadrupolar Carr–Purcell–Meiboom–Gill (QCPMG) spectra of stationary powdered samples have been acquired at multiple high magnetic field strengths (11.7, 14.1, and 21.1 T) to determine their composition and number of aluminum sites, which were analyzed to extract detailed information on the aluminum electric field gradient (EFG) and nuclear magnetic shielding tensors. The quadrupolar parameters for each 27Al site were determined from spectral simulations, with quadrupolar coupling constants (CQ) ranging from 5.40 to 10.0 MHz and asymmetry parameters (η) ranging from 0.10 to 0.50, and compared well with the results of quantum chemical calculations of these tensors. We also report the largest 27Al chemical shielding anisotropy (CSA), with a span of 120 ± 10 ppm, observed directly in a solid material. The combination of MQMAS and computational predictions are used to interpret the presence of multiple aluminum sites in two of the three samples.

Induction of Liposome Leakage by Photodynamic Action: Dependence on the Kind of Fluorescent Probe

Photosensitized damage to liposome membranes was studied by using different dye-leakage assays based on fluorescence dequenching of a series of dyes upon their release from liposomes. Irradiation of liposomes with red light in the presence of a photosensitizer, trisulfonated aluminum phthalocyanine (AlPcS3), resulted in the pronounced leakage of carboxyfluorescein, but rather weak leakage of sulforhodamin B and almost negligible leakage of calcein from the corresponding dye-loaded liposomes. The photosensitized liposome permeabilization was apparently associated with oxidation of lipid double bonds by singlet oxygen as evidenced by the requirement of unsaturated lipids in the membrane composition for the photosensitized liposome leakage to occur and the sensitivity of the latter to sodium azide. The fluorescence correlation spectroscopy measurements revealed marked permeability of photodynamically induced pores in liposome membranes for such photosensitizers as AlPcS3 and AlPcS4. It was proposed that the difference in permeability of these pores to carboxyfluorescein and calcein was associated with size restriction. Verification of this hypothesis by studying the effect of PEGs of different molecular weights is under way.

Light-Triggered Liposomal Release: Membrane Permeabilization by Photodynamic Action

Photosensitized damage to liposome membranes was studied by using different dye-leakage assays based on fluorescence dequenching of a series of dyes upon their release from liposomes. Irradiation of liposomes with red light in the presence of a photosensitizer, trisulfonated aluminum phthalocyanine (AlPcS(3)), resulted in the pronounced leakage of carboxyfluorescein, but rather weak leakage of sulforhodamine B and almost negligible leakage of calcein from the corresponding dye-loaded liposomes. The same series of selectivity of liposome leakage was obtained with chlorin e6 that appeared to be more potent than AlPcS(3) in bringing about the photosensitized liposome leakage. Electrically neutral zinc phthalocyanine tetrasubstituted with a glycerol moiety (ZnPcGlyc(4)) was less effective than negatively charged AlPcS(3) in provoking the light-induced liposome permeabilization. On the contrary, both ZnPcGlyc(4) and AlPcS(3) were much more effective than chlorin e6 in sensitizing gramicidin channel inactivation in planar bilayer lipid membranes, thus showing that relative photodynamic efficacy of sensitizers can differ substantially for damaging different membrane targets. The photosensitized liposome permeabilization was apparently associated with oxidation of lipid double bonds by singlet oxygen as evidenced by the mandatory presence of unsaturated lipids in the membrane composition for the photosensitized liposome leakage to occur and the sensitivity of the latter to sodium azide. The fluorescence correlation spectroscopy measurements revealed marked permeability of photodynamically induced pores in liposome membranes for such photosensitizer as AlPcS(3).

Reactive oxygen species produced by irradiation of some phthalocyanine derivatives

A comparative study of the reliability of methods used for the determination of singlet oxygen was carried out. The water iodide method, as well as the methods using 9,10-dimethylanthracene (DMA) and 1,3-diphenylisobenzofuran (DPIBF) in dimethylformamide (DMF) solutions, was used for the detection of singlet oxygen 1O 2 production in eight phthalocyanine photosensitizers. The iodide method is not only selective for the determination of 1O 2 but can also be used for the determination of other oxygen species. In addition, the results of the iodide method are affected by a possible formation of phthalocyanine dimers and by post-irradiation reactions. On the other hand, both the methods using indicators in DMF are highly selective for the determination of 1O 2. The quantum yield of the singlet oxygen production was determined for eight phthalocyanine derivatives; the following sequence was obtained: 5 ∼ 4 > 7 ∼ 2 ∼ 8 (standard) > 6 > 3 ∼ 1, where 5 represents the ammonium salt of disulphonated zinc phthalocyanine, 4 sulphonated zinc phthalocyanine [(3-diethylammonium)-propylsulphonamide] citrate, 7 tetrakis(trimethylammonium)zinc phthalocyanine tetraiodide, 2 tetrakis( N-methylpyridinium-3-oxy)zinc phthalocyanine tetraiodide, 8 zinc phthalocyanine, 6 sodium salt of disulphonated aluminum phthalocyanine, 3 sulphonated aluminum phthalocyanine [( N-2-hydroxyethyl)aminoethylsulphonamide] and 1 tetra-methylenepyridinium chloride of hydroxyaluminum phthalocyanine.